(5x-5)(14x+28)=0

Solution for (5x-5)(14x+28)=0 equation:

(5x-5)(14x+28)=0

We multiply parentheses ..

(+70x^2+140x-70x-140)=0

We get rid of parentheses

70x^2+140x-70x-140=0

We add all the numbers together, and all the variables

70x^2+70x-140=0

a = 70; b = 70; c = -140;
Δ = b2-4ac
Δ = 702-4·70·(-140)
Δ = 44100
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{44100}=210$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(70)-210}{2*70}=\frac{-280}{140}
=-2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(70)+210}{2*70}=\frac{140}{140}
=1
$